BitBox: Instant Bitcoin on a Hardware Wallet
Who's BitBox?
If you've held bitcoin for any length of time, you've probably considered a BitBox. Designed and built in Switzerland by Shift Crypto, a startup spun off from ETH Zurich in 2015, the BitBox02 and BitBox02 Nova pair secure chips with fully open-source firmware. It's the hardware wallet you'd recommend to your parents.
The strength of BitBox is keeping users' bitcoin on lockdown, and until now that made it hard to spend. That's the hardware wallet dilemma: the better it protects your savings, the harder it is to spend your money. Users already manage their devices with the BitBoxApp, and BitBox wanted to let them store and spend their bitcoin with the app too.
The Challenge
Nobody plugs in a hardware wallet to buy a coffee. So BitBox users have done what most hardware wallet users do: use a second app for spending, with a second seed phrase to look after. They were stuck with savings in one place, spending in another, and ferrying sats between the two manually.
To make the BitBoxApp a non-custodial wallet and not just a vault, BitBox explored different options. They took Blockstream's Greenlight to MVP, but it wasn't reliable enough to ship. An Ark prototype followed. Ark requires wallets to go online regularly, which rules out a wallet people open only for payments. BitBox needed full wallet functionality that would categorically improve their users' payment experience with no compromises.
The Solution
BitBox integrated the Breez SDK directly into the BitBoxApp, which let them add the functionality they needed without a second seed phrase. Savings stay secure inside the BitBox hardware, while users can spend frictionlessly from the app on their phones.
For users:
- Speed: Scan a QR code at the counter and pay instantly from your phone while your savings stay safe inside your BitBox at home.
- Convenience: Top up from the BitBox when you want to spend, move bitcoin back when you want to save, and claim your own Lightning address to get paid, all without leaving the BitBoxApp.
- One backup: The spending wallet is derived from users' existing backups, so there are no new recovery words to write down and store. If a user loses their phone, their existing BitBox backup recreates the keys for the spending wallet. Neither BitBox nor Breez ever touches them.
For developers:
The task was specific: a spending wallet that works together with cold storage and uses a single backup. The BitBox derives a seed from its existing backup using BIP-85, and the Breez SDK runs everything from there. There is no node to run, no channels to open, and no liquidity to source. Top-ups from the hardware wallet are automated inside the app, which also makes them more secure.
Where the earlier experiments faltered, the Breez SDK excels. The BitBox team was most surprised by the SDK's reliability, its steady improvement during the integration, and how fast payments settle.
"Breez has been incredibly helpful and responsive when dealing with our requests, observations, and doubts. This is how you get other teams happily integrating your solution."
Luca, Developer at BitBox
For growth:
Instant payments are live in public beta on the mobile BitBoxApp for every BitBox owner, and they're just one setting away. The companion app for the cold wallet is now where users manage and spend their bitcoin too.
BitBox built its name keeping bitcoin out of reach. Now its users can spend their money in seconds, and the keys never leave their hands.
Ready to Get Started?
Join BitBox and the world's best builders adding instant, non-custodial bitcoin and stablecoins with the Breez SDK.